<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <title>网站简介</title>
    <style type="text/css">
    body {
        background: url("../images/sl.jpg") 0 / cover fixed;
        text-align: center;
    }
    
    a {
	position: relative;
	display: inline-block;
	outline: none;
	text-decoration: none;
	color: #000;
	font-size: 32px;
	padding: 5px 10px;
}

a:hover::before, a:hover::after { position: absolute; }
a:hover::before { content: "\5B"; left: -20px; }
a:hover::after { content: "\5D"; right:  -20px; }
    </style>
</head>

<body>
    <a>123</a>
</body>

</html>
